Skip to content
All Models

GPT-5.1-Codex

openai/gpt-5.1-codex

GPT-5.1-Codex is a GPT-5.1 generation coding agent model designed for autonomous software engineering, combining improved reasoning over the GPT-5 codex generation with the ability to read, write, execute, and verify code in sandboxed environments.

File InputTool UseReasoningVision (Image)Web SearchImplicit Caching
index.ts
import { streamText } from 'ai'


const result = streamText({
  model: 'openai/gpt-5.1-codex',
  prompt: 'Why is the sky blue?'
})

What To Consider When Choosing a Provider

  • Zero Data Retention

    AI Gateway supports Zero Data Retention for this model via direct gateway requests (BYOK is not included). To configure this, check the documentation.

    Authentication

    AI Gateway authenticates requests using an API key or OIDC token. You do not need to manage provider credentials directly.

GPT-5.1-Codex builds on the GPT-5 codex foundation with the GPT-5.1 generation's improvements in reasoning and instruction following, translating to better code quality and more reliable autonomous task completion.

For maximum compute on the hardest coding problems, consider GPT-5.1 codex max. For routine tasks, codex mini provides faster, cheaper results.

When to Use GPT-5.1-Codex

Best For

  • Autonomous feature development:

    Writing complete features from specifications with test verification

  • Complex debugging:

    Tracing issues through large codebases and producing verified patches

  • Multi-file refactoring:

    Changes that span modules and require understanding architectural patterns

  • Code migration:

    Converting codebases between frameworks, languages, or API versions

  • Comprehensive test generation:

    Creating thorough test suites that cover edge cases and failure modes

Consider Alternatives When

  • Hardest coding challenges:

    GPT-5.1 codex max applies maximum compute for the most demanding tasks

  • Routine coding tasks:

    Codex mini handles simpler bug fixes and scaffolding more efficiently

  • General-purpose work:

    GPT-5.1 instant or thinking for non-coding tasks

  • Budget constraints:

    Earlier codex models at lower price points for cost-sensitive pipelines

Conclusion

For teams that want GPT-5.1 generation coding capability without the compute premium of codex max, GPT-5.1-Codex is the practical middle ground. It handles autonomous coding workflows reliably and slots into AI Gateway alongside other codex variants.

FAQ

It benefits from the GPT-5.1 generation's advances in reasoning and instruction following, producing better code quality and more reliable autonomous task completion.

When tackling the most complex coding challenges where maximum compute and reasoning depth are worth the additional cost, such as large-scale architectural changes or critical security audits.

400K tokens, enabling comprehensive codebase understanding in a single pass.

Yes. It operates in sandboxed environments where it can execute code and run test suites to verify its output.

AI Gateway accepts a single API key or OIDC token for all requests. You don't embed OpenAI credentials in your application; AI Gateway routes and authenticates on your behalf.

This page shows live throughput and time-to-first-token metrics measured across real AI Gateway traffic.